| Summary: | 博士 === 國立中正大學 === 電機工程所 === 94 === Deregulation of the electricity industry has been taking place in several countries. It will bring about significant changes in generation and transmission patterns. In a competitive market environment, deregulation of the electricity industry and transmission open access make it important to fairly allocate the cost of transmission service, and determine the power contribution of generators to lines and loads as well as the power contribution of lines to loads. Customers will no longer deal with one integrated electric utility. As a result, customers will get power through wheeling. Therefore, study on power flow tracing is getting more attention in recent years.
Those power flow tracing methods do not allow concluding which one is best, and they are not possible to demonstrate the validity of the key principles that support each of the methods. In this dissertation, three methods, the Graph theory-proportional sharing principle tracing method, the T-model tracing method and the inserted tracing method, for power flow tracing are proposed. The proposed method can deal with the problem of reactive power decomposition which cannot be resolved previously when convection transmission lines are encountered. Moreover, the proposed method provides possible allocation of line loss to individual generators or loads, and that is useful for line service charging.
In the Graph theory-proportional sharing principle tracing method, graph theory and proportional sharing principle are used for power flow tracings and evaluation of contributive flow of individual generators to line flows.
In the T-model tracing method, an equivalent line model derived from the nominal- circuit for reactive power decomposition is presented. Graph theory and proportional sharing principle are employed to trace power flow.
In the inserted tracing method, the overall power flow is considered to be composed of two parts. The first part is the power flow generated by transmission line capacitance charging. The second part is the power flow determined neglecting line capacitance charging. The first part of power flow is decomposed according to the contribution ratios of generators or loads to lines obtained from the decomposition results to the first part. Graph theory and proportional sharing principle are employed to trace power flow, which is then employed to determine the real power contribution of generators to lines and loads and the reactive power contribution of generators and lines to loads.
An IEEE 30-bus system is used to demonstrate the effectiveness of the proposed method, and the results from the proposed power flow tracing methods are compared with that from the Newton Raphson’s AC power flow. From these results, it is observed that the line flows obtained by applying the proposed tracing and decomposing are extremely close to the results obtained by the Newton Raphson’s AC power flow.
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